Blurry/blocky scanlines

[Former user]

Hi, the scanlines blur in your NTSC emulation doesn't seem to work properly.. There is so much blur horizontally. It looks very blocky. But when I reduce the 'sharpness' parameter, it starts to look better... Strange. I use Retina MacBook Pro and Safari, latest em-fceux version.

[Valtteri Heikkilä]

Fix #26 'Blurry/blocky scanlines'

→ <<cset 1a7c7446361b>>

[Valtteri Heikkilä]

Cause was from giving negative values to sqrt() in the sharpening fragment shader. One should never do that as the output for negative input is undefined. (Same goes for pow().)